Elastic polyurethane-urea fiber and method for producing the same

ABSTRACT

An improved polyurethane-urea elastic fiber is obtained by incorporating a specific urea compound prepared by reacting the following compounds together: 
     (a) a nitrogen-containing compound having both at least one bifunctional amine group selected from a group consisting of a primary amine group and a secondary amine group and at least one nitrogen-containing group selected from a group consisting of a tertiary nitrogen group and a heterocyclic nitrogen group; 
     (b) an organic diisocyanate; and 
     (c) at least one compound selected from the group consisting of a mono- or di-alkylmonoamine, an alkylmonoalcohol and an organic monoisocyanate. 
     With the incorporation of the specific urea compound, the polyurethane-urea elastic fiber which can be fast dyed exhibits enhanced thermosettability and increased elastic functions can be produced through a stabilized spinning process. The improved thermosetting property enables end use products of the present fiber such as swimsuits and panty hose to be firmly shaped and to be substantially free from grinning.

TECHNICAL FIELD

The present invention relates to a polyurethane-urea elastic fiberexcellent in thermosettability and dyeability. Further, it relates to amethod for producing a polyurethane-urea elastic fiber having a goodelastic function as well as providing a favorable spinning stability.

BACKGROUND ART

A polyurethane-urea elastic fiber is known which is obtained by chainextending an isocyanate-terminated prepolymer synthesized by reactingpolyalkylene ether glycol with organic diisocyanate in excess quantityby diamine. The polyurethane-urea elastic fiber has been used as astretchable functional material while being mixedly knit or woven withpolyamide fiber and/or polyester fiber for various fields of clothing,such as foundation garment, socks, panty hose, swim suits, sports wear,leotards or others.

The polyurethane-urea elastic fiber forms strong physical crosslinkingof hydrogen bonds, caused by hard segments composed of an urea group,and exhibits an excellent elastic function. However, when thepolyurethane-urea elastic fiber is used for fields wherein ashape-retaining property of a product fabric is particularly required;for example, a circular knit fabric field including leg wear such aspanty hose or tights, a warp knit fabric filed including underwear andsports wear such as brassieres, girdles or swim suits, or a woven fabricfield including outer wear such as bottom suit; processing anintermediate product thereof is problematic in that, because thepolyurethane-urea elastic fiber is poor in thermosettability, anintermediate product could not be finished into a predetermined sizethereby resulting in formation of a finished product inconvenient forwearing, or a hem of the fabric is liable to curl up to disturb thesewing operation.

Also, when the product is set to have a predetermined width, it isnecessary to repeat the setting operation or setting at a relativelyhigh temperature for obtaining a desired result, which deteriorates theproductivity and the heat efficiency.

Other elastic fibers having no urea groups but similar to thepolyurethane-urea elastic fiber, such as polyurethane elastic fiber(elastic fiber solely composed of urethane bonds) or polyether-esterelastic fiber (polyester copolymerized with polyalkyleneether glycolcomponent), are also known. While these elastic fibers are excellent inthermosettability and shape-retaining property, they have no hardsegments composed of urea groups, and therefor are problematic in thatthe elastic function is liable to be damaged; i.e., the elastic recoveryis inferior to the polyurethane-urea elastic fiber or the stretchingfatigue becomes larger than that of a polyurethane-urea elastic fiber.In other words, they lack wear-comfort and durability for use as utilityclothing. Particularly, the polyether ester elastic fiber not only lackselongation as an elastic fiber but also has a larger variation in stressrelative to the elongation to result in a tight feeling notcorresponding to the physical motion. Also, since these elastic fibersare poor in heat-durability, the elastic fibers in the fabric may bedamaged or broken in the field, for example, of stretch outer wear inwhich a high-temperature treatment is necessary or the field, forexample, of foundation garment which is difficult to color-match andnecessitates the repetition of dyeing, whereby the aesthetic appearanceof the products is deteriorated.

Thus, if thermosettability could be imparted to the polyurethane-ureaelastic fiber without sacrificing the heat-durability and the elasticfunction thereof, this fiber could be advantageously used in suchfields.

For the purpose of improving the thermosettability of polyurethane-ureaelastic fiber with an excellent elastic function, a polyurethane-ureaelastic fiber is proposed, in Japanese Unexamined Patent Publication(Kokai) No. 3-97915, which is mainly composed of polyether and in whicha terminal prepolymer of isocyanate is chain-extended with a specificmixed diamine, and another polyurethane-urea elastic fiber is proposed,in Japanese Unexamined Patent Publication (Kokai) No. 8-113824, in whichdiamine, monoamine and prepolymer are polymerized with each other at aspecific ratio. In Japanese Unexamined Patent Publication (Kokai) No.7-150417 a polyurethane-urea elastic fiber in which an alkali metal saltis incorporated therein at a low concentration. The applicant of thisapplication has also disclosed, in Japanese Unexamined PatentPublication (Kokai) No. 7-316922, a further polyurethane-urea elasticfiber and a method for producing the same in which a thermoplasticpolymer of any of a specific polyacrylonitrile type polymer, a specificpolyurethane polymer and a specific styrene-maleic anhydride copolymerin a range from 1 to 14% by weight is added. However, in all cases, theimprovement in thermosettability of the conventional polyurethane-ureaelastic fiber is discernible but may be unsatisfactory as well as therebeing cases in which the elastic function of the polyurethane-ureaelastic fiber may be sacrified or the yarn breakage may occur to disturbthe spinning operation.

The polyurethane-urea elastic fiber is always mixed with polyamide fiberor polyester fiber and is subjected to a dyeing treatment. An acid dyeis mainly used for dyeing the mixture with the polyamide fiber. Sincethere is no seat group for the acid dye in the polyurethane-ureapolymer, most of the dye is distributed to the polyamide fiber, whilethe elastic fiber is hardly dyed. On the other hand, a disperse dye ismainly used for dyeing the mixture with the polyester fiber. Althoughthe disperse dye easily enters the elastic fiber, it is almost allremoved therefrom during the reduction-scouring treatment after thedyeing whereby the elastic fiber is hardly dyed. There may be a casewherein the elastic fiber appears to be dyed if the reduction-scouringtreatment is insufficient. In such a case, the dye is removed from theelastic fiber during the laundering or dry-cleaning to deteriorate thecolor fastness as a whole. Particularly, when dyed in a deep color, ifthe elastic fiber is not dyed even though the polyamide or polyesterfiber has been dyed, there is a problem in that the color tone of thefabric lacks the deepness or the elastic fiber shines brightly orwhitely when the fabric is stretched (a so-called “grinning”).

There have almost been no proposals in the prior art for satisfactorilysolving the above-mentioned problems, by an improvement in thepolyurethane-urea fiber itself, or methods for producing apolyurethane-urea elastic fiber excellent in thermosettability as wellas in elastic function under the stable spinning condition.

An object of the present invention is to solve the above problems in theprior art and provide a polyurethane-urea elastic fiber excellent inelastic function, heat-durability and thermosettability as well asimproved in dyeability to have a good color fastness. Another object ofthe present invention is to provide a polyurethane-urea elastic fibercapable of manufacturing a fabric excellent in dyeability,shape-retaining property and elastic function as well as free from thegrinning phenomenon. A further important object of the present inventionis to provide a method for producing a modified polyurethane-urea fiberexcellent in elastic function, as described above, in a stable spinningstate.

DISCLOSURE OF THE INVENTION

The present inventors have found that a polyurethane-urea elastic fibercontaining a specific urea compound, described later, could be modifiedto be uniquely excellent in elastic function and heat-durability as wellas have good thermosettability and dyeability, and such a modified fibercould be produced under a stable spinning condition. Thus, the presentinvention has been completed.

The present invention is a polyurethane-urea elastic fiber obtained byincorporating a urea compound, in a range from 1 to 15% by weight, in apolyurethane-urea polymer, the urea compound being prepared by reactingtogether the following compounds:

(a) a nitrogen-containing compound having at least one bifunctionalamine group selected from a primary amine and a secondary amine, andhaving at least one nitrogen-containing group selected from a tertiarynitrogen and a heterocyclic nitrogen,

(b) an organic diisocyanate, and

(c) at least one compound selected from a group consisting of a mono- ordi-alkylmonoamine, an alkylmonoalcohol and an organic monoisocyanate.

The polyurethane-urea elastic fiber and a method for producing the sameaccording to the present invention will be described, in more detail,below.

The urea compound used for the present invention is prepared by reactingtogether (a) a nitrogen-containing compound having at least onebifunctional amine group selected from a primary amine and a secondaryamine, and having at least one nitrogen-containing group selected from atertiary nitrogen and a heterocyclic nitrogen, (b) an organicdiisocyanate, and (c) at least one compound selected from a groupconsisting of a mono- or di-alkylmonoamine, an alkylmonoalcohol and anorganic monoisocyanate. It is necessary to regulate chemical molarequivalents of the above-mentioned (a), (b) and (c) prior to thereaction so that no active terminals are left in the resultant ureacompound.

The resultant urea compound contains a tertiary nitrogen skeleton asshown in the following equation (3) and urea bonds as shown in thefollowing equations (4) and (5):

In this regard, when alkylmonoalcohol is reacted, a urethane bond shownin the following equation (6) is contained:

The urea compound according to the present invention is classified intothe following two kinds of structure (7) and (8) satisfying the aboveequations (3) to (6) in accordance with the selection of the compound(c).

i) If mono- or di-alkylmonoamine or alkylmonoalcohol is selected for(c),

(c)-[(b)-(a)]n-(b)-(c)  (7)

ii) If organic monoisocyanate is selected for (c),

(c)-[(a)-(b)]n-(a)-(c)  (8)

 (wherein n is the repetition number of polymerization and is one ormore). The structure shown in the equation (8), in which the organicmonoisocyanate is selected from (c), is more preferable.

Preferably, urea compounds of the two kinds of structures are used aloneseparately. However, they may be used in the mixed state.

The nitrogen-containing compound having at least one bifunctional aminegroup selected from compounds (a) consisting of a primary amine and asecondary amine, and having at least one nitrogen-containing groupselected from a tertiary nitrogen and a heterocyclic nitrogen includes,for example, N-butyl-bis(2-aminoethyl)amine,N-butyl-bis(2-aminopropyl)amine, N-butyl-bis(2-aminobutyl)amine,N,N-bis(2-aminoethyl)-isobutylamine,N,N-bis(2-aminopropyl)-isobutylamine,N,N-bis(2-aminoethyl)-t-butylamine, N,N-bis(2-aminoethyl)-1,1-dimethylpropylamine, N,N-bis(2-aminopropyl)-1, 1-dimethylpropylamine,N,N-bis(2-aminobutyl)-1, 1-dimethylpropylamine,N-(N,N-diethyl-3-aminopropyl)-bis(2-aminoethyl)amine,N-(N,N-dibutyl-3-aminopropyl)-bis(2-aminopropyl)amine, piperazine,piperazine derivatives such as 2-methylpiperazine,1-(2-aminoethyl)-4-(3-aminopropyl)piperazine, 2,5- and2,6-dimethylpiperazine, N,N′-bis(2-aminoethyl)piperazineN,N′-bis(3-aminopropyl)piperazine, N-(2-aminomethyl)piperazine,N-(2-aminoethyl)piperazine or N-amino-(2-aminoethyl)-4-methylpiperazine,piperidine derivatives such as 4-aminoethylpiperidine,N-amino-4-(2-aminoethyl)piperidine, N-bis(2-aminoethyl)aminepiperidine,and pyrrolidone derivatives such asN-amino-4-(2-aminoethyl)-2-pyrrolidone,N-(3-aminopropyl)-4-(3-aminopropyl)-2-pyrrolidone,N-bis(2-aminoethyl)amine-2-pyrrolidone. Piperazine and piperazinederivatives are preferable nitrogen-containing compounds. Particularly,N-(2-aminoethyl)piperazine and N-(2-aminopropyl)piperazine are suitablebecause of their extremely favorable solubility to an amide type solventof the resultant urea compound. These may be used alone separately or ina mixture.

The organic diisocyanate selected from compounds (b) for obtaining theurea compound according to the present invention includes, for example,trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylenediisocyanate, hexamethylene diisocyanate,3-methylhexane-1,6-diisocyanate, 3,3′-dimethylpentane-1,5-diisocyanate,1,3- and 1,4-cyclohexylene-diisocyanate,4,4′-dicyclohexylmethane-diisocyanate, m- and p-xylylene diisocyanate,α, α, α′,α′-tetramethyl-p-xylylene diisocyanate, 4,4′-diphenylmethanediisocyanate, isophorone diisocyanate and 2,4-tolylene diisocyanate.Alicyclic diisocyanates such as isophorone diisocyanate or4,4′-dicyclohexylmethane-diisocyanate are preferably used. These may beused alone separately or in a mixture.

The mono- or di-alkylmonoamine selected from compounds (c) for obtainingthe urea compound according to the present invention is a monoaminehaving alkyl group having carbon atoms in a range from 1 to 10,including, for example, isopropylamine, n-butylamine, t-butylamine,diethylamine, 2-ethylhexylamine, diisopropylamine, di-n-butylamine,di-t-butylamine, di-isobutylamine and di-2-ethylhexylamine. Also,tertiary nitrogen atoms or oxygen atoms may be contained in the alkylchain, which includes, for example, 3-dibutylaminopropylamine,3-diethylamino-propylamine, 3-ethoxypropylamine and3-(2-ethylhexyloxy)propylamine. These may be used alone separately or ina mixture.

Further, the alkylmonoalcohol in the compounds (c) used for obtainingthe urea compound according to the present invention is a mono alcoholhaving an alkyl group having carbon atoms in a range from 1 to 10,including, for example, methanol, ethanol, 2-propanol,2-methyl-2-propanol, 1-butanol, 2-ethyl-1-hexanol and3-methyl-1-butanol. These may be used separately or in a mixture.

The above-mentioned mono- or di-alkylamine and alkylalcohol may be usedalone in separate or in a mixture. The separate use is preferable.

Further, the organic monoisocyanate in the compounds (c) used forobtaining the urea compound according to the present invention includes,for example, n-butyl isocyanate, phenyl isocyanate, 1-naphtylisocyanate, p-chlorophenyl isocyanate, cyclohexayl isocyanate, m-tolylisocyanate, benzyl isocyanate and m-nitrophenyl isocyanate. These may beused separately or in a mixture. However, they are inhibited from beingmixed with the above-mentioned mono- or di-alkylamine or alkylalcohol,because a compound in which active hydrogen is hindered by the organicmonoisocyanate is generated to decrease an effective amount of the ureacompound of the structure represented by the equation (7) or (8).Moreover, such a compound bleeds out during the treatment process forthe polyurethane-urea elastic fiber, causing scum which contaminates aknitting machine and a dyeing bath.

The compound (c) used for the urea compound according to the presentinvention, which is selected from the three kinds of compounds asdescribed above, blocks active terminals (amino group or isocyanategroup) of the urea compounds obtained from the compounds (a) and (b).The active terminal deteriorates the spinning stability of thepolyurethane-urea elastic fiber or lowers the color fastness. If thereactive molar equivalent of (a) is larger than that of (b), the ureacompound is terminated with amino groups, whereby the organicmonoisocyanate must be selected from the compounds (c), while if thereactive molar equivalent of (a) is smaller than that of (b), the ureacompound is terminated with isocyanate groups, whereby at least one ofmono- or dialkylamine and alkylmonoalcohol must be selected from thecompounds (c). Preferably, the organic monoisocyanate is selected asdescribed before.

The urea compound according to the present invention is characterized byhaving urea bonding units represented by the following equations (9) and(10) in a range from 4 to 40, as an average value, in one molecule. Inthis regard, the average value is a number-average value.

If the compound (c) is mono- or di-alkylmonoamine or alkylmonoalcohol,the structure of the urea compound is represented by the equation (11)(wherein n represents the repetition number of polymerization which isone or more):

The urea compound having a desired average number of urea bonding unitsis obtainable by the adjustment of the reactive molar ratio between thecompounds (a), (b) and (c). That is, if it is adjusted to be(a):(b):(c)=n:n+1:2, the average number of urea bonding units in onemolecule becomes 2n+2 in the mono- or di-alkylmonoamine and 2n in thealkylmonoalcohol.

If the compound (c) is organic monoisocyanate, the structure of the ureacompound is represented by the equation (12) (wherein n represents therepetition number of polymerization which is one or more):

If it is adjusted to be (a):(b):(c)=n+1:n:2, the average number of ureabonding units in one molecule becomes 2n+2.

The urea compound according to the present invention has the averagenumber of urea bonding units in one molecule is in a range from 4 to 40.If it is converted to the repetition number n of polymerization in thestructure, it is in a range from 1 to 19 in a case of the mono- ordi-alkylmonoamine and organic monoisocyanate, and in a range from 2 to20 in a case of the alkylmonoalcohol. If the average number of ureabonding units is less than 4 or more than 40, the thermosettabilitybecomes insufficient. Further, if the average number of urea bondingunits is less than 4, scum may be generated due to bleed-out during thetreatment process of the polyurethane-urea elastic fiber, resulting inthe color contamination of a knitting machine and a dye bath. Also, ifthe average number of urea bonding units exceeds 40, the urea compoundmay be separated out from a polyurethane-urea spinning dope to causeyarn breakage during the spinning operation or to lower the elongationof the polyurethane-urea elastic fiber, whereby the elastic functionthereof is deteriorated. The average number of urea bonding units ispreferably in a range from 4 to 15 in one molecule.

The number of urea bonding units existing in one molecule of the ureacompound according to the present invention is adjustable in accordancewith molar ratios between (a), (b) and (c). A reaction temperature ispreferably in a range from 20 to 60° C. The reaction is preferablycarried out in an amide type polar solvent in which thepolyurethane-urea polymer is soluble, such as dimethylformamide,dimethylacetamide or N-methylpyrrolidone. When a solvent in which thepolyurethane-urea polymer is insoluble is used, it is possible todissolve solid component product obtained after the reaction in anothersolvent in which the polyurethane-urea polymer is soluble and add thesolution to the polyurethane-urea polymer.

As one example of the reaction, 2 mols of N-(2-aminomethyl)piperazineselected from (a), 1 mol of isophorone diiscyanate selected from (b) and2 mols of phenylisocyanate selected from (c) are reacted with each otherat 50° C. for 2 hours to result in a dimethylacetamide solution of 50%by weight. The reaction may be carried by dripping isophoronediisocyanate and phenylisocyanate into N-(2-aminomethyl)piperazinedissolved in dimethylacetamide. However, the reaction should not belimited thereto but includes other known methods. The urea compound thusobtained has the repetition number of polymerization n of 1, and thenumber of urea bonding units of 4 in one molecule.

The polyurethane-urea elastic fiber according to the present inventionmay be obtained by dry-spinning a spinning dope prepared by adding theurea compound dissolved in the amide type polar solvent to the solutionof polyurethane-urea polymer. The addition could be carried out at anoptional stage from the completion of the polymerization ofpolyurethane-urea polymer until the initiation of the spinning.

An amount of the urea compound to be contained in the polyurethane-ureaelastic fiber according to the present invention may be such that thesettability and the dyeability necessary for the resultant fabric aresatisfactory unless the elastic function and the spinning stability aredamaged; which is preferably in a range from 1 to 15% by weight relativeto the polyurathane-urea polymer. If the amount of the urea compound tobe added is less than 1% by weight, the thermosettability and thedyeability become inferior. Contrarily, if it exceeds 15% by weight, aneffect of the thermosettability is saturated not only to deteriorate thecolor fastness but also to disturb the spinning stability due to thegeneration of yarn breakage as well as to lower the elastic functionsuch as strength, elongation or elastic recovery. A preferable amount isin a range from 2 to 10% by weight.

In this respect, although the thermosetting effect may be improved ifthe urea compound is added to a polyurethane elastic fiber (an elasticfiber consisting solely of urethane bonds), an extent of the improvementis less than that when the same is added to the polyurethane-ureaelastic fiber, and, in addition, the elastic function and the spinningstability of the polyurethane elastic fiber may be deteriorated.

Known arts for improving the thermosettability may be also used formodifying the polyurethane-urea elastic fiber according to the presentinvention. For example, at least one kind of thermoplastic polymerselected from a group consisting of a polyacrylonitrile type polymer,polyurethane polymer and styrene-maleic anhydride copolymer described inJapanese Unexamined Patent Publication (Kokai) No. 7-316922 may besimultaneously contained in combination with the urea compound,according to the present invention. Preferably, in such a case, a totalamount of the thermoplastic polymer and the urea compound according tothe present invention is 15% by weight or less, and an amount of thethermoplastic polymer does not exceed that of the urea compoundaccording to the present invention.

It is not clear why the polyurethane-urea elastic fiber containing theurea compound according to the present invention exhibits an excellentthermosettability and dyeability without sacrificing theheat-duribility, elastic function and spinning stability. However, oneexplanation is as follows. The excellent dyeability and color fastnessmay be caused by the effect of a specific nitrogen-containing compound,i.e., that of the urea compound containing a specific number of ureabonding units. In other words, it is surmised that a nitrogen-containingcompound having at least one bifunctional amine group selected from aprimary amine and a secondary amine, and having at least onenitrogen-containing group selected from a tertiary nitrogen and aheterocyclic nitrogen, strongly adsorbs and retains the acid dye ordisperse dye.

On the other hand, it is surmised that the excellent thermosettabilityis derived from the urea compound having the average number of ureabonding units in a range from 4 to 40. The polyurethane-urea elasticfiber is a segmented polymer having urethane bonds and urea bonds. Ofthem, the urea bonds build an extremely strong physical crosslink of ahydrogen bond between them to form a crystalline domain. Accordingly,this fiber exhibits an excellent elastic function under the normaltemperature but is difficult to be heat-set because the hydrogen bond ishardly broken even at a high temperature. The urea compound, accordingto the present invention, having a specific number of urea bonding unitsstrongly hydrogen-bonds to the urea bonds in the polyurethane-ureaelastic fiber to merge into a crystalline domain in thepolyurethane-urea elastic fiber, resulting in the polyurethane-ureaelastic fiber exhibiting an excellent elastic function under normaltemperature. However, the urea compound according to the presentinvention is operative to lower a glass transition point of thecrystalline domain. Thus, the hydrogen bond is broken under a hightemperature, whereby the crystalline domain easily heat-flows to resultin the polyurethane-urea elastic fiber excellent in thermosettability.If an amount of the urea compound according to the present invention isexcessively small relative to the polyurethane-urea elastic fiber, thethermosetting effect becomes insufficient. On the other hand, ifexcessively large, the thermosetting effect becomes satisfactory but theglass transition point of the crystalline domain lowers too much,whereby a heat flow is generated, due to the high temperature, duringthe spinning operation to not only disturb the spinning stability butalso to damage the elastic function.

The polyurethane-urea polymer according to the present invention isprepared from a polymer glycol having hydroxyl groups at oppositeterminals and having a number-average molecular weight in a range from600 to 5000, an organic diisocyanate, a chain extender of diaminecompound and a terminal blocker of monoamine compound. The polymerglycol includes, for example, various diols consisting of substantiallylinear homo- or copolymer, such as polyester diol, polyether diol,polyesteramide diol, polyacryl diol, polythioester diol, polythioetherdiol or polycarbonate diol, or mixtures thereof or copolymers thereof.Of them, polyalkyleneether glycol is preferable, including, for example,polyoxyethylene glycol, polyoxypropylene glycol, polytetramethyleneether glycol, polyoxypentamethylene glycol, polyether-glycol copolymerconsisting of tetramethylene group and 2,2-dimethylpropylene group,polyether-glycol copolymer consisting of tetramethylene group and3-methyltetramethylene group and mixtures thereof. Of them,polytetramethylene ether glycol, polyether-glycol copolymer consistingof tetramethylene group and 2,2-dimethylpropylene group is preferablebecause of its excellent elastic function. The organic diisocyanate usedfor the polyurethane-urea polymer according to the present invention maybe optionally selected from aliphatic, alicyclic and aromaticdiisocyanates, provided it is soluble in an amide type polar solvent orliquefied under the reactive condition. It includes, for example,4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate,2,4-and 2,6-tolylene diicocyanate, m- and p-xylylene diisocyanate, α, α,α′,α′-tetramethyl-xylylene diisocyanate, 4,4′-diphenyletherdiisocyanate, 4,4′-dicyclohexyl diisocyanate, 1,3- and 1,4-cyclohexylenediisocyanate, 3-(α-isocyanateethyl)phenylisocyanate, 1,6-hexamethylenediisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate andisophorone diisocyanate, mixtures thereof and copolymers thereof. Ofthem, 4,4′-diphenylmethane diisocyanate is preferable.

The diamine compound used as a chain extender in the polyurethane-ureapolymer according to the present invention includes, for example,ethylenediamine, 1,2-propylenediamine, 1,3-diaminocyclohexane,2-methyl-1,5-pentadiamine, hexamethylenediamine, triethylenediamine,m-xylylenediamine, piperazine, o-, m- and p-phenylenediamine, a diaminehaving urea group which is described in Japanese Unexamined PatentPublication (Kokai) No. 5-155841 and mixtures thereof. Of them,ethylenediamine alone, or mixtures of ethylenediamine containing 5 to 40molar % of at least one kind selected from a group consisting of1,2-propylenediamine, 1,3-diaminocyclohexane and2-methyl-1,5-pentadiamine are preferred.

The monoamine compound used as a terminal blocker in thepolyurethane-urea polymer according to the present invention includes,for example, a monoalkylamine such as isopropylamine, n-butylamine,t-butylamine or 2-ethylhexylamine, and a dialkylamine such asdiethylamine, diisopropylamine, di-n-butylamine, di-t-butylamine,di-isobutylamine, di-2-ethylhexylamine, which may be used alone or as amixture. Also, 1,1-dimethylhydrazine may be mixed with the abovemonoamine compound.

The polyurethane-urea polymer can be prepared by a knownpolyurethane-urea reaction technology. For instance, an excessive molaramount of organic diisocyanate is reacted with polyalkyleneether glycolhaving a number-average molecular weight in a range from 600 to 5000 inan amide type polar solvent to prepare an intermediate polymer havingisocyanate groups at the terminals. Then, the intermediate polymer isdissolved in an amide type polar solvent to react the chain extenderwith the terminal blocker, resulting in the polyurethane-urea polymer.

The polyurethane-urea elastic fiber according to the present inventionis obtainable by the dry spinning of a dope in which the urea compoundaccording to the present invention in a range from 1 to 15% by weight iscontained in the polyurethane-urea polymer.

Organic or inorganic compounding agents, other than the urea compoundaccording to the present invention, useful for known polyurethane-ureaelastic fiber, polyurethane elastic fiber and/or polyurethane compoundmay be added simultaneously or sequentially to the spinning dope, suchas an ultraviolet absorber, antioxidant, light stabilizer, gas-resistantanti-coloring agent, colorant, delusterant, lubricant or others.

The spinning dope of polyurethane-urea polymer obtained in such a mannermay be spun into a fiber form through a known dry or wet spinning methodto be a polyurethane-urea elastic fiber. The dry spinning method ispreferable in view of the superiority in elastic function andproductivity.

The polyurethane-urea elastic fiber preferably has a large singlefilament size in view of an improvement in thermosettability. Apreferable range of the single filament size is from 6 to 33 dtx. Thisis because the relaxation of orientation is larger in a crystallinedomain of the fiber structure. If the single filament size is less than6 dtex, the orientation is too large, while if it exceeds 33 dtex, thecrystalline size becomes too large although the relaxation oforientation becomes small, in both of which cases the crystalline flowbecomes difficult during the heat-set treatment. This is true not onlyof the pourethane-urea elastic fiber but also of all kinds of elasticfibers.

A thermosettability used in the present invention is defined by thecombination of a wet-heat treatment at 120° with a dry-heat treatment at120° C. Since the elastic fiber is often dried by heated air after beingsubjected to a wet-heat treatment (steam set or dyeing) in an actualprocess, the thermosettability used in the present invention is moresuitable for the actual circumstances than the estimation based solelyon the dry- or wet-heat treatment. The polyurethane-urea elastic fiberaccording to the present invention preferably has the thermosettabilitydefined by the present invention of 50% or more. If this value is lessthan 50%, problems are liable to occur, such as insufficientshape-retaining property of the resultant product or generation ofhem-curling in the resultant fabric. The thermosettability is morepreferably 60% or more.

The polyurethane-urea fiber according to the present inventionpreferably has a strength-retaining ratio of 50% or more after beingdry-heated at 180° C. If it is less than 50%, the heat-durabilitybecomes too low and the elastic fiber in the fabric is worn or broken bya high-temperature treatment, setting or redyeing of the fabric. Morepreferably, the strength-retaining ratio is 60% or more.

The resultant polyurethane-urea elastic fiber may be imparted withpolydimethylsiloxane, polyester-modified silicone, polyether-modifiedsilicone, amino-modified silicone, mineral oil, mineral particulate suchas silica, colloidal alumina or talc, higher fatty acid metallic powdersuch as magnesium stearate or calcium stearate, oil in a solid formunder the normal temperature such as higher aliphatic carboxylic acid,higher aliphatic alcohol, paraffin or polyethylene, which are used aloneor as optionally being mixed if necessary.

The polyurethane-urea elastic fiber according to the present inventionis seldom knitted or woven alone but is mixedly knitted or woven with anatural fiber such as cotton, silk or wool, a polyamide fiber such as N6or N66, a polyester fiber such as polyethylene terephthalate fiber,polytrimethylene terephthalate fiber, or polytetramethyleneterephthalate fiber, a cation-dyeable polyester fiber, cuprammoniumrayon, viscose rayon or acetate rayon, or covered, entangled or twistedwith the latter fibers to form a finished yarn which is then knitted orwoven to form a fabric.

The fabric obtained from the polyurethane-urea elastic fiber accordingto the present invention may be used for swim suits, a stretchablefoundation garment such as girdles, brassiere or intimate goods,underwear, an elastic band for a sock-top, tights, panty hose, waistbands, body suits, spats, stretchable sportswear, stretchable outerwear,bandages, supporters, medical wear, stretchable liners or paper diapers.

BEST MODES FOR CARRYING OUT THE INVENTION

Prior to describing the preferred embodiments of the present invention,various measurements for estimating the performance thereof and a methodfor preparing panty hose will be explained below.

[1] Measurement of Strength at Break, Elongation at Break and ElasticRecovery

A test yarn of 5 cm long is subjected to a tensile test by using atensile tester (Type UTM-III-100 manufactured by Kabushikikaisha TOYOBALDWIN in the atmosphere of 20° C., 65% RH at a stretching speed of 50cm/min to obtain a strength at break (g) and an elongation at break (%).

Elastic recovery is estimated as a stress-retaining ratio (%) at 200%elongation by repeating three times the stretching of the test yarn from0 to 300%, from which the modulus thereof at 200% elongation aremeasured in the forward and backward paths of the third cycle. Thestress-retaining ratio (%) at 200% elongation is calculated by thefollowing equation (13)

Stress-retaining ratio (%) at 200% elongation =(fR/fS)×100  (13)

wherein fR is a modulus at 200% elongation in the forward path of thethird cycle of the repeated stretching from 0 to 300%, and fS is amodulus at 200% elongation in the forward path of the third cycle of therepeated stretching from 0 to 300%. The higher the stress-retainingratio at 200% elongation, the more excellent the elastic recovery.

[2] Estimation of Heat-durability

A test yarn of 14 cm long is stretched to be 21 cm and brought intocontact with a stainless steel pillar having a surface temperature of185° C. (the portion of the pillar to be in contact with the test yarnis approximately 1 cm). A time period (in second) is measured until thetest yarn is broken by heat. The longer the time period, the higher theheat-durability. If the fiber is excellent in heat-durability, theresultant fabric does not become thin or lean even after being dyed, setor redyed at a high temperature and the yarn in the fabric is free fromyarn breakage.

[3] Estimation of Thermosettability

A test yarn having an initial length of 5 cm is elongated by 100% andleft in an atmosphere of pressurized steam at 120° C. for 15 seconds,after which it is dried in a dryer at 120° C. for 30 seconds. Then, itis relaxed in an atmosphere at 50° C. for 1 hour. Further, after it isleft in an atmosphere at 20° C. and 65% RH for 16 hours, a length (L cm)of the test yarn is measured. In this regard, the relaxation at 50° C.is a treatment for accelerating the change with time. Thethermosettability is calculated from the following equation (14):

Thermosettability (%)=(L-5)/5×100  (14)

The higher the thermosettability, the more excellent the shape-retainingproperty of the fabric.

[4] Estimation of Strength-retaining Ratio After Being Dry-heated at180° C.

A test yarn having an initial length of 5 cm is heat-treated while beingstretched at 100% elongation in a dryer at 180° C. for 1 minute. Afterbeing left in an atmosphere at 25° C. and 60% RH for 16 hours, astrength at break of the test yarn is measured in accordance with themethod defined in [1]. Although a length of the test yarn is changedfrom the initial length, the measurement is carried out in a portioncorresponding to the initial length of 5 cm. A ratio (%) of the strengthat break of the treated test yarn relative to that of the untreated testyarn is defined as a strength-retaining ratio. The higher the ratio, thehigher the heat-durability; thus the fabric does no become thin or leaneven after the high temperature dyeing, high-temperature setting andredyeing and the yarn in the fabric is free from yarn breakage.

[5] Estimation of Dyeability and Color Fastness

A bare knit fabric is prepared from test yarns by using a circularknitting machine (CR-C type, manufactured by KOIKE KIKAI SEISAKUSHOK.K.). The bare knit fabric of 1.2 g weight is put into a stainlesssteel container together with a bare knit fabric obtained from polyamidefibers of 4.8 g weight and dyed with an acid milling dye (black) 4% owfat a bath ratio of 1:50, pH 4.0, 90° C. for 60 minutes. After beingsubjected to a fixing treatment and treated with a softener, the knitfabric is rinsed with water and air-dried, after which a dyed state isestimated according to a five-grade estimation system consisting ofcriteria from a fifth grade (most-deeply dyed) to a first grade(most-palely dyed). The higher the grade, the deeper and more preferablethe dyed color.

The above-mentioned dyed bare knit fabric of 1 g weight and thepolyamide fiber bare knit fabric of 1 g weight are laundered with a 0.8g/L detergent solution of 300 cc. After being rinsed with water, theknit fabric is air-dried. The dyed state of the bare knit fabric of thetest yarns is estimated according to five-grade estimation system. Thehigher the grade, the deeper and more preferable the dyed color. Also,the color contamination of the polyamide fiber bare knit fabric isestimated in accordance with the five-grade estimation system consistingof criteria from a fifth grade (most-palely color-staining) to a firstgrade (most-deeply color-staining). The higher the grade, the less thecolor-staining.

[6] Preparation of Panty Hose

A polyamide elastic fiber (manufactured by ASAHI KASEI KOGYO K.K.;Leona, 11 dtex/5f) and a test yarn are subjected to a covering treatment(a draft ratio of 2.7 and the number of twists of 1600 T/m; to obtaintwo single-covered S-twist yarns and two Z-twist yarns, respectively).The covered yarns are fed to a knitting machine (NAGATA SIMPLEX KT-6type; 400 gauges) through all of four yarn holes to knit a so-called“Zokki” (high-quality) panty hose of 2500 total courses (a panty hosewherein all the courses are knit from the covered yarns). The knitfabric is preset at 50° C., and then dyed at 95° C. for 45 minutes.After being subjected to a fixing treatment and treated with a softener,the knit fabric is put on a foot mold and heat-set with a pressurizedsteam at 120° C. for 15 seconds, after which it is dried at 120° C. for30 seconds. The knit fabric is taken off from the foot mold and left inan atmosphere of 20° C. and 65% RH for three days.

[7] Estimation of Thermosettability of Panty Hose

A length (cm) of a leg section of the panty hose prepared as describedabove is measured. The longer the length, the better thethermosettability of the test yarn used therein.

[8] Estimation of Spinning Stability

When a polyurethane-urea spinning dope is made to pass through a 40 μmNASLON (phonetic) filter (manufactured by NIPPON SEISEN K.K.) anddry-spun through two orifices of 0.15 mmφ of a spinneret at 230° C. toresult in a polyurethane-urea elastic fiber of 17 dtex/2f, a take-upspeed is initially fixed at 300 m/min for five minutes and thengradually increased until yarn breakage occurs in a spinning tube.Assuming that the take-up speed at which the yarn breakage occurs is Xm/min, an extremity of a single filament size represented by thefollowing equation (15) is used for estimating the spinning stability:

Extremity of a single filament size (dtex)=(17/2)×300/X  (15)

The smaller the extremity of a single filament size, the better thespinning stability.

EXAMPLES

While the present invention will be more concretely described withreference to examples, it should be appreciated that the presentinvention is not limited thereto.

Example 1

1500 g of polytetramethylene ether glycol having a number-averagemolecular weight of 1800 and 312 g of 4,4-diphenylmethane diisocyanatewere agitated together to be reacted with each other in a nitrogen gasstream at 60° C. for 90 minutes to result in polyurethane prepolymerhaving isocyanate groups. Then, the prepolymer was cooled to a roomtemperature and added with dry dimethylformamide of 2600 g to obtain apolyurethane prepolymer soloution. On the other hand, 23.4 g of ethylenediamine and 3.7 g of diethylamine were dissolved into 1400 g of drydimethylformamide, which solution was added to the above-mentionedprepolymer solution at a room temperature to result in apolyurethane-urea polymer solution having a viscosity of 320 pascal.sec(30° C.).

Isobutylene addition product of polyaddition compound of p-cresol anddicyclopentadiene at 1.5% by weight,N,N-bis(2-hydroxyethyl)-t-butylamine at 2.5% by weight,2-(2′-hydroxy-3′,5-dibenzyl-phenyl)benzotriazole at 0.3% by weight,magnesium stearate at 0.05% by weight, and urea compound at 6% by weightconsisting of N-(2-aminiethyl)piperazine, 4,4-diphenylmethanediisocyanate and phenylisocyanate (a molar ratio of 2:1:2) to have anaverage number of urea bonding units of 4 was added to the resultantpolymer solution to be a spinning dope.

The spinning dope was dry-spun at a spinning speed of 600 m/min and ahot air temperature of 230° C. to obtain a polyurethane-urea elasticfiber of 17 dtex/ 2f.

Examples 2 to 5

The urea compound used in Example 1 was replaced by that of 6% by weightconsisting of N-(2-aminiethyl)piperazine, isophorone diisocyanate andphenylisocyanate (a molar ratio of 2:1:2) to have an average number ofurea bonding units of 4, that of 8% by weight consisting ofN,N-bis(2-aminoethyl)-1, 1-dimethylpropylamine, isophorone diisocyanateand cyclohexyl isocyanate (a molar ratio of 3:2:2) to have an averagenumber of urea bonding units of 6, that of 8% by weight consisting ofN-(2-aminoethyl)piperazine, hexamethylene diisocyanate and t-butylamine(a molar ratio of 2:3:2) to have an average number of urea bonding unitsof 6, and that of 8% by weight consisting of N-(2-aminoethyl)piperazine,isophorone diisocyanate and 1-butanol (a molar ratio of 3:4:2) to havean average number of urea bonding units of 6, respectively, andpolyurethane-urea elastic fibers were spun in the same manner as inExample 1.

Example 6

The urea compound of 8% by weight used in Example 2 having an averagenumber of urea bonding units of 17 (a molar ratio of 17:15:4) was addedand a polyurethane-urea elastic fiber was spun in the same manner as inExample 1.

Example 7

Instead of the urea compound in Example 1, polyurethane polymer of 4% byweight described in Example 4 of Japanese Unexamined Patent Publication(Kokai) No. 7-316922 (polyurethane polymer consisting of 1,4-butanediol,polytetramethylene ether glycol having a number-average molecular weightof 650 (a molar ratio of 9:1) and 4,4′-diphenylmethane-diisocyanate (amolar ratio of 0.99:0.11:1) having a number-average molecular weight of30000) and urea compound of 4% by weight consisting ofN,N′-bis(3-aminopropyl)piperazine, isophorone diisocyanate andphenylisocyanate (a molar ratio of 2:1:2) to have an average number ofurea bonding units of 4 were added instead of the urea compound used inExample 1, and a polyurethane-urea elastic fiber was spun in the samemanner as in Example 1.

Comparative Examples 1 to 3

Polyurethane-urea elastic fibers were manufactured while changingamounts of the urea compound to be added in Example 1 to 0, 0.4 and 18%by weight, respectively.

Comparative Example 4

The urea compound used in Example 2 adjusted to have an average numberof urea bonding units 45 (a molar ratio of 45:43:4) was added at 8% byweight, and a polyurethane-urea elastic fiber was spun in the samemanner as in Example 1. However, the spinning was impossible becauseyarn breakage often occurred.

Comparative Example 5

In Example 7, a polyurethane-urea elastic fiber was produced byadjusting the urethane compound to 8% by weight and the urea compound to0% by weight.

Comparative Example 6

Potassium benzoate of 0.12% by weight described in Example 1 of KokaiNo. 7-150417 was added instead of the urea compound used in Example 1,and a polyurethane-urea elastic fiber was spun.

The estimation results of a strength at break, elongation at break,elastic recovery, heat durability, strength-retaining ratio after beingdry-heated at 180° C., thermosettability, dyeability, color fastness andspinning stability of the polyurethane-urea elastic fibers obtained fromExamples 1 to 7 and Comparative examples 1 to 6 are shown in Tables 1and 2.

TABLE 1 Composition of urea compound to be added Urea compound One kindselected from mono- or di- alkylmonoamine, Amount to be alkylmonoalcohol(a):(b):(c) Number added to Nitrogen-containing Organic and organicReactive of urea polyurethane- compound diisocyanate monoisocyanatemolar bonding urea polymer (a) (b) (c) ratio units (% by weight) Knownart Example 1 N-(2-aminoethyl)piperazine 4,4′- phenylisocyante 2:1:2 46.0 — diphenylmethane diisocyanate Example 2 N-(2-aminoethyl)piperazineisophorone phenylisocyanate 2:1:2 4 6.0 — diisocyanate Example 3N,N-bis(2-aminoethyl)-1, isophorone cyclohexyl 3:2:2 6 8.0 —1-dimethylpropylamine diisocyanate isocyanate Example 4N-(2-aminoethyl)piperazine hexamethylene t-butylamine 2:3:2 6 8.0 —diisocyanate Example 5 N-(2-aminoethyl)piperazine isophorone 1-butanol3:4:2 6 8.0 — diisocyanate Example 6 N-(2-aminoethyl)piperazineisophorone phenyl isocyanate 17:15:4 17 8.0 — diisocyanate Example 7N,N-bis(3- isophorone phenyl isocyanate 2:1:2 4 4.0 Polyurethane polymerof 4.0% aminoethyl)piperazine diisocyanate by weight described in Exam-ple 4 of Kokai No. 7-316922 Comparative not added — example 1Comparative N-(2-aminoethyl)piperazine 4,4′- phenyl isocyanate 2:1:2 40.4 — example 2 diphenylmethane diisocyanate ComparativeN-(2-aminoethyl)piperazine 4-4′- phenyl isocyanate 2:1:2 4 18.0 —example 3 diphenylmethane diisocyanate ComparativeN-(2-aminoethyl)piperazine isophorone phenyl isocyanate 45:43:4 45 8.0 —example 4 diisocyanate Comparative — — — — — — Polyurethane polymer of8.0% example 5 by weight described in Exam- ple 4 of Kokai No. 7-316922Comparative — — — — — — Potassium benzoate of 0.4% example 6 by weightdescribed in Exam- ple 1 of Kokai No. 7-150417

TABLE 2 Performance and processibility of fiber Elastic function Heatdurability Elastic Time lapse recovery until fiber Strength- Dyeabilityand colot fastness Spinning (stress- in contact retaining Dyed statestability retaining with a hot ratio after Dyed of knit Color Extremityof ratio (%) at pillar at being dry- state fabric after contaminationsingle Strength Elongation 200% 185° C. is heated at Thermosettabilityof knit being of polyamide filament at break at break elongation) broken180° C. Thermosettability fabric laundered fiber size (g) (%) (%)(seconds) (%) (%) (grade) (grade) (grade) (dtex) Example 1 26 590 56 3265 70 5 4 4 1.8 Example 2 25 585 55 36 69 68 5 4 4 1.5 Example 3 25 56554 30 63 67 5 4 4 2.1 Example 4 29 606 52 34 64 67 4 4 5 2.0 Example 526 578 54 32 65 65 4 4 5 2.0 Example 6 24 563 50 35 70 62 4 4 4 2.2Example 7 26 551 49 38 67 68 5 5 5 2.1 Comparative 26 596 56 38 72 32 21 3 1.9 example 1 Comparative 27 587 55 37 71 38 2 2 4 1.9 example 2Comparative 14 465 38 12 46 75 5 4 2 3.5 example 3 ComparativeImpossible to be spun — — — — — — — example 4 Comparative 26 477 35 3367 42 2 1 3 3.2 example 5 Comparative 25 574 56 37 70 48 2 1 3 2.0example 6

Examples 8 to 10 and Comparative Examples 7 to 9

Zokki panty hose were formed by using the polyurethane-urea elasticfibers obtained from Examples 1, 2 and 7 and Comparative examples 1, 5and 6.

The estimation results of the panty hose obtained from Examples 8 to 10and Comparative examples 7 to 9 are shown in Table 3.

TABLE 3 Estimation of the inventive products Estimation of thermo-settability of panty hose Length of leg section of Test yarn used forZokki panty hose (cm) knitting Example 8 61 Example 1 Example 9 63Example 2 Example 10 58 Example 7 Comparative 47 Comparative example 1example 7 Comparative 50 Comparative example 5 example 8 Comparative 48Comparative example 6 example 9

It is apparent from Tables 1 to 3 that the polyurethane-urea elasticfiber according to the present invention is high in thermosettability,excellent in dyeability to result in a good color fastness and superiorin elastic function and heat durability, and can be spun in a stablemanner.

CAPABILITY OF EXPLOITATION IN INDUSTRY

Since the polyurethane-urea elastic fiber according to the presentinvention is excellent in shape-retaining property during the heatsetting, dyeability during the dyeing process, color fastness tolaundering, heat durability and elastic functions, it is suitable forthe production of an elastic fabric excellent in elastic functions,capable of being fast dyed, durable against a heat treatment, good inshape-retaining property and free from “grinning”. Thus, the presentinvention provides an elastic fiber material excellent in elasticfunctions and good in processibility usable for all fields of fabricssuch as, as examples, a circular knit fabric such as panty hose, socksor tights, a warp knit fabric such as foundation wear or swim suits anda woven fabric such as outer wear. Particularly, the polyurethane-ureaelastic fiber according to the present invention is suitable for Zokkipanty hose or warp- or weft-stretchable woven fabric.

What is claimed is:
 1. A polyurethane-urea elastic fiber obtained byincorporating a urea compound in a range from 1 to 15% by weight in apolyurethane-urea polymer, which urea compound is prepared by reactingthe following compounds together: (a) a nitrogen-containing compoundhaving at least one bifunctional amine group selected from a primaryamine and a secondary amine, and having at least one nitrogen-containinggroup selected from a tertiary nitrogen and a heterocyclic nitrogen, (b)an organic diisocyanate, and (c) at least one compound selected from agroup consisting of a mono- or di-alkylmonoamine, an alkylmonoalcoholand an organic monoisocyanate.
 2. A polyurethane-urea elastic fiber asdefined by claim 1, wherein the urea compound contains average number ofurea bonding units ranging from 4 to 40 in one molecule, represented bythe following equations (1) and (2):


3. A polyurethane-urea elastic fiber as defined by claim 1 or 2, whereinthe nitrogen-containing compound is at least one kind selected from agroup consisting of piperazine and bifunctional piperazine derivatives.4. A polyurethane-urea elastic fiber as defined by any one of claims 1to 3, wherein the compound (c) is an organic monoisocyanate.
 5. Apolyurethane-urea elastic fiber as defined by any one of claims 1 to 4,wherein a single filament size is in a range from 6 to 33 dtex.
 6. Apolyurethane-urea elastic fiber as defined by any one of claims 1 to 5,wherein a thermosettability is 50% or more, and a strength-retainingratio is 50% or more after being dry-heated at 180° C.
 7. A method forproducing a polyurethane-urea elastic fiber, wherein an intermediatepolymer having isocyanate groups at terminals by reacting an excessivemolar amount of organic diisocyanate with polyalkylene ether glycolhaving a number-average molecular weight in a range from 600 to 5000, adiamine compound and a monoamine compound are reacted with each other toobtain a polyurethane-urea polymer, and a urea compound obtained frombifunctional piperazine derivative, organic diisocyanate and organicmonoisocyanate is added to the polyurethane-urea polymer in a range from1 to 15% by weight, all of which are then dissolved into an amide typepolar solvent to result in a polyurethane-urea solution which is thendry-spun to become the polyurethane-urea elastic fiber.